Preparation and properties of a novel alginate/carrageenan crosslinked coordination polymer and evaluation of the antibacterial, antioxidant and anticancer potential of its Co(<sc>ii</sc>), and Cr(<sc>iii</sc>) polymeric complexes

Natural polysaccharides play a crucial role across diverse fields such as medicine, food, and cosmetics, for their various physiochemical and biological properties. In this study, we developed a new crosslinked biopolymer using sodium alginate (AG) and carrageenan (CAR) polysaccharides. Various metal complexes involving different metal salts such as CoCl2<middle dot>6H2O and CrCl3<middle dot>6H2O were synthesized using the crosslinked biopolymer formed above. The two polymeric complexes were characterized using Fourier-transform infrared spectroscopy (FT-IR), elemental analysis, ultraviolet-visible spectroscopy (UV-Vis), magnetic susceptibility, molar conductivity techniques, and thermogravimetric analysis. The Co(ii) polymeric complex exhibits a tetrahedral X-ray crystal structure and belongs to the monoclinic crystal system. Cr(iii) complex is octahedral and crystal data are in compliance with the cubic crystal system. The antimicrobial study showed a significant activity improvement for all the developed complexes against both Gram-positive as well as Gram-negative bacterial pathogens - Staphylococcus aureus, Microscus luteum, Escherichia coli and Salmonella typhimurium. Similarly, the different polymeric complexes showed an efficient activity against Candida albicans as anti-fungal effect. Moreover, higher antioxidant values of the two complexes were obtained with DPPH scavenging activity ranging between 73% and 94%. In addition, both the polymeric complexes were subjected to biocompatibility cell viability assays along with in vitro anticancer evaluation. The alginate/carrageenan crosslinked coordination complexes revealed excellent cytocompatibility with normal human breast epithelial cells (MCF10A) and a high anticancer potential with human breast cancer cells (MCF-7) which increase significantly in a dose-dependent manner.